Police were called out to control a crowd of concert-goers unhappy after shock rocker Marilyn Manson, featured attraction at a "Freakers Ball" event Thursday night sponsored by KQRC 98.9 The Rock, ended his show early when fans pushed down a barrier.

According to accounts from people attending the concert at the Kansas City International Raceway, a security fence between the fans and the stage was pushed down twice, and after the second time the Manson band left the stage.

Some of the fans began rushing toward the stage, upset that the concert had been cut short. Kansas City Police Capt. Robert Zimmerman said some threw bottles at off-duty police officers who were hired to provide security at the concert.

"The crowd became unruly," he said. "We ended up calling in what we call a field force. It involved approximately 100 officers."

The officers, some wearing protective helmets, came from nearby Independence and Lee's Summit as well as Kansas City. Some fans said irritant sprays were directed at them as police took action to control the crowd.

Concert-goer Rodney Borden said that crews began taking down the band's equipment after the fence went down a second time and the musicians walked off.

"Everybody started just getting all freaked out and rioting after that," he said. "Cop cars were getting smashed. Cops were trying to get everybody out of there, and people were just fighting back. They wouldn't do what they got to do, just leave."

"It was like total chaos," said another young man.

"People are nuts," said Darrick Knight. "That's why I don't go to rock concerts that much."

The concert had started in the afternoon, and Manson's group was the last of six acts to perform. Zimmerman said about 12,000 people attended the concert.

Ambulances were at the scene, but apparently there were only a few minor injuries.

According to the Marilyn Manson Website, the band is scheduled to perform in Dallas Friday night.